Questions tagged [orbital-elements]

Orbital elements are a set of parameters that uniquely identify a specific orbit.

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Naming conventions concerning element sets/coordinate systems/reference frames

Suppose I have two ECI Cartesian state vectors: One in the TEME frame of reference and one in the GCRF frame of reference. Suppose I now convert both state vectors to Classical Orbital Elements (COE). ...
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Issue with SGP4 modelling from scratch in MATLAB

I am trying to develop the code from this source , this research paper and from this too as same as bibliography of that aforementioned source. So, here as you can see at page 14, they have defined ...
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How can I calculate if a satellite is currently in sunlight or eclipse using pyEphem or Skyfield (preferred)?

I'd like to add this to some existing python scripts to model cubesat battery life and payload temperature but the math escapes me.
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Orbital period from TLE data [duplicate]

Is there a way to calculate the orbital period from the Two Line Element (TLE) data?
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Mean to Osculating conversion for non-J2 averaged elements

What is the appropriate technique to convert mean elements (true anomaly averaged) into osculating elements when the model has J2, SRP, drag and additional forces modeled. Brouwer's transformation is ...
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How can I convert a Walker constellation (i: t/p/f) to cartesian position and velocity coordinates (ECI)?

I need to convert a Walker constellation (i: t/p/f) to cartesian position and velocity coordinates relative to earth center (ECI) -- i.e., position x,y,z and velocity x,y,z. Standard Anaconda Python ...
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1answer
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How frequent do TLEs of LEO satellites change?

I was doing some MATLAB simulations on LEO satellites using TLEs obtained from n2yo websites and I observed that n2yo was displaying a different TLE for the same satellite after a few days. I don't ...
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How do I calculate the change in the argument of periapsis after a plane change maneuver?

Let's say I have a spacecraft in an initial geocentric orbit with the following parameters: a = 7,960,000 m, e = 0.010, $\Omega$ = 180$^{\circ}$, i = 98$^{\circ}$, $\omega$ = 90$^{\circ}$, $\theta_0$ =...
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Calculating orbital parameters for given requirements

I'm trying to determine what's the best way to calculate the required orbit for a LEO remote sensing satellite. I understand there exists the trade-off between sensor coverage and sensor accuracy, but ...
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Argument of Perigee for a circular orbit

For a perfectly circular orbit (e=0), how is the argument of perigee defined?? Thanks.
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Where can I find examples of orbital state vectors?

I'm currently trying to write a program that can calculate orbital trajectories. The goal is to take any orbital state vector (position, velocity) and convert it into Keplerian orbital elements, or ...
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Can the Right Ascension and Argument of Perigee of a spacecraft's orbit keep varying by themselves with time?

I came across the orbital data for a low Earth orbit spacecraft and one thing which I am not able to understand is why does its Right Ascension of ascending node and Argument of Perigee keep changing ...
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Finding Earth-Centered Coordinates of Periapsis

I am currently writing a program that accepts a state vector, calculates the corresponding Keplerian ellipse, and then draws the ellipse. But I'm stuck at the following point. I currently need some ...
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How to calculate angle in elliptic orbit?

I would like calculate angle in elliptic orbit ZCP at any time, where: Z (position of periapsis), C (center of ellipse), P (current position of planet). I find topic, where is picture (in accepted ...
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True Anomaly of Circular Orbit

How would you calculate the true anomaly of a circular orbit (e=0)? I'm trying to design an orbit for a mission on STK and so I'm not sure what the eccentric anomaly (in order to calculate true ...
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Compute heliocentric ecliptic coordinates from Kepler's laws

I'm writing a program to compute the heliocentric ecliptic position of planets and asteroids. I want to output rectangular coordinates oriented according to the ecliptic: positive X in the direction ...
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How to obtain the initial positions and velocities of an inclined orbit?

I have (x,y,z) initial positions and (vx,vy,vz) initial velocities in a coplanar orbit with respect to the reference frame. If I change the inclination of this orbit with the angle i, how I can ...
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How to get true anomaly using subsatellite point (latitude)?

I am working on an application which is using an orbit propagator. I have a satellite which sets its latitude using this orbit propagator. I want to change the latitude of the satellite by a new value,...
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What is wrong with my orbit sim equations? How can I fix them?

Edit: Partial question: The object now moves in an ellipse like it's supposed to, but it orbits around a different point than I intend. How can I make it orbit around a particular object at a point? ...
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1answer
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Is software available for writing two line element files from Keplerian elements?

I am interested in writing a TLE file from existing Keplerian elements. Is software available on the web to do this?
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1answer
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NAIF and SpiceyPy returning seemingly inaccurate results

I am yet another amateur astrophysics enthusiast creating a solar system simulator. I began by hard-coding planetary bodies and their satellite orbiting characteristics via JPL data tables such as ...
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Help needed with obtaining position vector of Spacecraft in Heliocentric-Ecliptic frame

I have been now using the ephemeris table attached as an image. It gives the orbital elements of all planets on Jan 1 2000 calculated from Heliocentric-Ecliptic frame. The current planetary orbital ...
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Deviation of semi-major axis

If I calculate the semi-major axis of Molniya-1T with $a = \sqrt[3]{\dfrac{GM}{n^2}}$ with $n=3.18683728\text{ }d^{-1}$, I get another apoapsis ($a=19505.7$ km) as noted at Heavens Above: apogee ...
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Generating JPL HORIZONS parameters for use with JPL HORIZONS itself

I want to be able to calculate RA/Dec for a given body with JPL HORIZONS, using a heliocentric specification of the orbital elements for a small solar system body (say, Apophis), but instead of using ...
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1answer
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Simulating a nanosatellite lunar flyby

I am trying to create a Lunar Flyby mission for small nanosatellites and I want to plot an orbit for it. The problem is that no website has proper information as to what variables, problems and ...
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1answer
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TA of the intersection of 2 orbits with different AoP

Two orbits are given with the same orbital elements, except the argument of perigee (AoP). How to calculate the true anomaly (TA) of the intersection of the orbits? Currently, I calculate it ...
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How accurate can a satellite's orbit be?

How precise can an artificial satellite be when it comes to following the exact orbit in relation to Earth or hitting the same point above Earth in orbit? Which orbit would be the most stable for this?...
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What are common guidance strategies for a finite orbital maneuver?

Suppose we have our spacecraft in a circular orbit around the Moon and we want to transfer it to an elliptic orbit with a medium-thrust (10-100N) retrograde burn. Based on the current state estimate, ...
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Calculating t(E)

The mean radius vector of an elliptic orbit is equivalent to the semi-major axis. If I sample the radius vector of an unperturbed elliptic orbit as a function of the eccentric anomaly with at a ...
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How can I calculate Mean anomaly from True longitude?

So, I have - TLE data - Reference frame: QMOD - Type: Osculating - Semimajor axis - Eccentricity - Asceding node - ...
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1answer
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Comparison of AOP change of the orbits

I'm comparing how the Argument of perigee (AOP) changes for 2 orbits (O1 and O2). The orbits ...
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1answer
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different ways to calculate satellite height

I found 2 formulas for calculating height. First is: height = magnitude(satillate_position_vector) - Earth_radius Second is: ...
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computing radial, along track, cross track components (differences) from two ECEF coordinates and velocities [closed]

I need to compute radial, along track, cross track components (differences) for two points in the orbital planes. I found the unit vectors of radial, along track, cross track but couldn't sure how ...
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Is it possible to plot the ground track of a satellite with just azimuth & elevation angles without range?

I came across this question on StackOverflow about Satellite Trajectory plot. In the code mentioned in the question, the user takes only the Azimuth & Elevation angles (radians) & converts ...
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How to calculate the orbital distance between 2 satellites given the TLEs

I have 2 LEO satellites with the same orbital plane with same inclination & longitude of the ascending node. I have the TLEs for each satellite. How do I calculate the orbital distance between the ...
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1answer
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What is the angle between two orbits in the equatorial plane?

My orbit is in the equatorial plane. When i apply thrust in the y or x axis, it rotates around the focus or planet - see red and blue orbit in the image below. I know the the semi-major-axis and ...
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Need help with calculating state vectors from Orbital Elements - C#

I have been working on a project where I want to visualize the orbits in the solar system with the help of Unity Engine. I have been using different guides and similar questions on this forum to ...
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What is hyperbolic eccentric anomaly F?

I have no idea what this is and have been searching on the net but all I get is eccentric anomaly. The equation that relates hyperbolic eccentric anomaly F to its true anomaly $\theta$ is exactly the ...
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GMAT starts simulating in 1990, how do I change that?

I'm running a simulation of a few satellites using their TLE epochs and other orbital parameters. GMAT gives the correct dates when writing the report output, but the contact locator and spacecraft ...
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1answer
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What are the symbol definitions in the equations for finding orbital elements?

I've been looking at the answer to this question on how to convert position and velocity to orbital elements, but some of the symbols are not defined and there are no reference links for those symbols....
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How to determine the optimal orbit for a LEO satellite

Our goal is to determine the best orbit that will allow a ground station (so this is a fixed point on earth) to communicate a maximum number of times par day with a LEO satellite. So the question is :...
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1answer
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TLE SGP4 Coordinate Transformations

I am working on developing a user friendly SGP4 orbit propagator in C on a PIC24. I have extensively read Revisiting Spacetrack Report #3 and celestrak - there are a few outstanding questions I have....
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simple example applying perturbed effect on orbit propogation?

I need to apply perturbation effect to orbit propagation. I am programmer not a physicist. I’ve already wrote program to propagate not perturbation orbit and show satellite ground track. So I know how ...
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1answer
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TLE data conversion to osculating orbit elements [closed]

I got the latest TLE from www.celestrak.com for a satellite. How could I convert it to osculating elements? Please, share some links/references.
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How to get velocity vector from GPS NMEA data?

I am writing a program to receive and interpret NMEA data from a GPS receiver. I am working with an Adafruit Ultimate GPS Receiver integrated with an Arduino. The $GPRMC NMEA Sentence contains the ...
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1answer
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Help with Cartesian State Vectors → Keplerian Orbit Elements C#

EDIT I am currently attempting to try the standard Cartesian State Vectors to Keplerian Orbit Elements conversion but i am having problems getting my head around the formulas and the use of vectors. ...
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1answer
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Algorithm to convert from ECEF coordinates to ECI coordinates

I am looking for an Algorithm (the formulas; not the code) to convert from ECEF coordinates to ECI coordinates. I have a MATLAB code for it but am unable to understand certain things. So it'd be ...
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1answer
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Applying secondary orbital perturbation effects

I read about secondary effects which influence on orbit propagation like solar radiation, moon, etc. (https://en.wikipedia.org/wiki/Orbit_modeling). First I calculate position vector Rpqw to object (...
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Why is the sidereal period of the Earth 362.392667 days?

Using JPL's Horizons API I can look at the orbital elements for the EM Barycenter wrt the Solar System Barycenter at J2000. The output looks like this: Watch for the PR (Sidereal orbit period) ...